Reading will drop below the freezing mark again tonight across Iowa. High pressure currently dropping into the Dakotas will settle into the state toward daybreak Tuesday, bringing with it light winds, clear skies, and a dry airmass, quite favorable for nighttime cooling. The warning does not extend to northern Iowa as those locations have not sufficiently progressed through the growing season to warrant issuance.
A freeze warning will be in effect from 1am to 9am Tuesday. Temperatures will fall below 32 degree after midnight, reaching overnight lows in the middle to upper 20’s, with a few locations dropping into the lower 20’s. Tender unprotected vegetation may be killed or damaged by the cold temperatures and resultant freeze.
A freeze warning means sub-freezing temperatures are imminent or highly likely. These conditions will kill crops and other sensitive vegetation.